Spark plug



y 2 H. SCHLAICH 2 Q SPARK PLUG Fil d July 1, 1926 lNVEN TOR HAW/14W Joe1mm ATTORNEY Patehted May 28, 1929.

UNITED STA'lES 1,714,521 PATENT OFFICE.

HERMAN SCHLAICH, LONG ISLAND CITY, NEW YORK.

SPARK YLUG.

Application filed July 1,

Thisinvention relates to spark plugs'and is in the nature of animprovement upon the spark plug shown in my pending application SerialNo. 103,200, filed April 20, 1926, en-

. element, the arrangement being such that the titled Spark plugs andspark intensifiers.

In said pending application disclosure is made of a spark plug in whichone of the electrodes is carried on a thermally responsive to causepre-ignition when the motor is otherwise in normal condition.

It is a further object of the invention to so construct the spark plugthat the s arking gap can never exceed a predetermine length.

In the accompanying drawings forming a part of this specification:

Figure 1 is a sectional plug and Figure 2 1s a bottom plan view thereof.The spark plug comprises a sleeve or body elevation in the spark portion1 threaded at its lower end for securement to a cylinder of an internalcombustion engine. A porcelain insulator 2 is seated in this bodyportion, being held therein by an externally threaded sleeve nut 3. Aconductive wire extends centrally through the insulator sleeve from abindingterminal 4 at the upper end of the insulator and terminates atits lower end in a central, fixed sparking terminal 5. A second sparkingterminal. 6 is carried by a thermally responsive element? consisting ofabi-metallic strip composed of metals having different (Io-efficients ofexpansion, said strip being formed as an arc of a volute spiral.

It is a point that this bi-metallic strip is mounted to lie within thelower end of the metallic body portion 1 of the spark-plug.

Forthis purpose said body portion 1 of the spark plug is provided with asmooth-walled,- circular internal rabbet or recess 8 at its lower end.The bi-metallic strip has outwardly projecting, integral fingers 9 whichare passed 7 be caused to occur.

body 1 is in contact with a water-cooled part advantage that it isimpossi 1926. Serial No. 119,819.

outward through openings in the lower end of the sparkplug body 1and'clinched at the outer side of said body.

The arrangement is such that when the m0- tor is cold, the lei-metallicstrip is out of contact with the spark plug body except at the endthereof which is attached to said body. The bi-metallic strip, however,lies withm the body in position toengage it when expanded by the heat.

With the construction described, the sparking gap is quite short uponthe startin of a cold motor, so that the spark may pass re'ely, eventhough the potential of the spark lug current is low, due to slowrotation of the generator. As the motor warms up, the bimetallic stripis caused to expand, so that the sparking terminal 6 is carried awayfrom the fixed terminal 5 and the length of the sparking gap isincreased. i

It is very important that heating of the bimetallic strip to atemperature which would cause pre ignition of the gases be avoided. Itis primarily for the purpose of guarding against such faulty operationthat the bimetallic strip is mounted within the bodyof the'spark plug.By such mounting, the hi metallic strip is caused to expand into contactthroughout its entire length with the bodyl before a temperature of-thelei-metallic strig has been reached at which pre-ignition wou Since thespark plug of the motor, it is always maintained at a safe operatingtemperature and is also efi'ective to controland limit the temperatureof the bismetallic strip when the bi-metallic strip moves into contactwith it.

The mountin of the bi-metallic strip within the body or t e spark plughas the further 10 for a careless car owner .or mechanic to distortthebi-"metallic stripmore than a predetermined, limited distance whenattemptingito clean the spark.

plug or to-adjiist the spar Such mounting has the Stfllfflrtheradvantage of positively limiting the length of the spark ap, so that thepassage of the spark when t e motor is warmed up cannot, under anycircumstances, be interfered with.

Variations maybe resorted'to Within the scopeLof the invention and partsof the improvements may be used without others. I claim:

1. In asphrk lug for internal combustion motors, the com ination with aspark plug body designed to engage a water-cooled part of the motor, ofa fixed sparking terminal, a second sparking terminal spaced therefrom,and a thermally responsive element carrying thesecond. sparkingterminal, said thermally responsive element being mounted on the sparkplug body and being movableby heating into contact with the spark plugbody throughout substantially its entire length before it has beenheated to an excessive temperature sufficient to ignite the gases,whereby such excessive heating is avoided.

2. In a spark plug, the combination with a heat dissipating spark plugbody, of an arcuate, bi-metallic strip mounted within the body, asparking terminal carried by said bimetallic strip, said sparkingterminal being movable by the bi-mctallic strip in response totemperature changes, and said bi-metallic strip being movable'to contactthespark plug body at a temperature b elow that at which pre-ignitionwould occur and being conformable in shape to said body at suchtemperature so that a large area of the bimetallic strip directlyengages the heat dissipating body.

3. In a spark plug, the combination with a spark plug body, of a fixedsparking terminal, a movable sparking terminal, and thermally responsivemeans mounted on the body and carrying the movable sparking terminal,said spark plug body and thermally responsive means being relativelyarranged to have extensive contact as the temperature rises and toarrest movement of the movable sparking terminal away from the fixedsparking terminal whereby the length of the spark gap is limited.

i. in a spark. plug, the combination with a fixed sparking terminal, ofa second sparking terminal, a thermally responsive element carrying thesecond sparking terminal and a heat dissipating shell supporting andsurrounding the thermally responsive element and engageable therewithover an extended area upon a predetermined distortion thereof to preventheating of said element to the ignition temperature, and thereby tomaintain the motor in efficient operation.

5. In a spark plug, in combination, a fixed sparking terminal, anarcuate second sparking terminal, a thermally responsive elementdisposed in a plane transverse to the axis of the spark plug andcarrying the second sparking terminal said element being distortable byheating to carry the second sparking terminal away from the first, andmeans surrounding the thermally responsive element and engageable overan extensive area therewith for arresting distortionthereof to limit thelength of the spark gap and the heating of the element.

6. In a spark plug, in combination a fixed sparking terminal, a secondsparking terminal, an arcuate thermally responsive element disposed in aplane transverse to the axis of the spark plug and carrying the secondsparking terminal said element being distortable by changes intemperature to move the second sparking terminal toward and from thefirst in a direction transverse to the spark plug axis, and a guardsurrounding the thermally responsive element to prevent injury theretoand to limit distortion thereof by heating.

7. In a spark plug, in combination, a first sparking terminal, a secondsparking terminal, a thermally responsive element carrying the secondsparking terminal and distortable by changes in temperature to move thesecond sparking terminal toward and from the first, and heat dissipatingmeans normally engaging a limited area of the element but arranged, upona predetermined heating of the thermally responsive element, to engagean extensive area thereof to prevent heatmg to the ignition temperature.

in testimony whereof l have aed my signature to this specification.

HERMAN dClilLhfGH.

near he. t e,

there ninhered patent renieirin eerreetien teller/e:

Granted liter 28, nee, te

it i herehy certified that error appears in printed eneeitiention of the2, line it, elaini h, ntrihe one the words "an nrennie" and insertinntearl the article "a", and

line-hi, ntrihe net the article "a" and insert instead the nerds anarennte"; and that ihe'eniel ltettere herein should he read with theseeerreetiene therein that in eae rnny eeninnn in the recent at the easein Patent @iiiee.

p heiinn hiene d heeled this 2nd day ei hilly, A. it. fifth.

J, Moore,

CERTIFICATE OF CORRECTION.

Patent No. 1,714,521. Granted May 28 1929, to

HERMAN SGHLAICH.

it is hereby certified that error appears in the erintetl speeiiicatieiiof the above numbered patent requiring correction as follows: Page 2,line 50 claim 5 strike out the words "an arcuate" and insert instead thearticle "a", and line 51, strike out the article "a" and insert insteadthe words "an arcuate"; and that the said Letters Patent should be readwith these corrections therein that the same may conform to the recordof the case in the Patent Qifice.

Signed and sealed this 2nd day of July, A. D. 1929.

M. J. Moore, (Seal) Acting Commissioner of Patents.

